In a flat panel display apparatus such as a liquid crystal display apparatus and an organic EL display apparatus, a display panel substrate and a chip-on-film (COF) substrate which mounts a driver IC are connected by thermal bonding using an anisotropic conductive film (ACF). Here, an ACF is a material obtained by mixing conductive particles to a bonding agent and forming the mixture into a tape. In an ACF connection, an ACF is sandwiched and thermally bonded between terminal parts of different substrates to electrically connect the terminals arranged vertically via conductive particles and insulate the terminals in each of the substrates at the same time, so that the substrates are bonded when the bonding agent is cured. Such ACF connection can be used in replacement for connection by connectors, and, compared with the case of using such connectors, enables connection on a thinner film substrate using a larger number of pins arranged at smaller pitches.
Patent Literature 1 discloses a flexible circuit substrate which is a COF substrate having a reduced wiring resistance. This flexible circuit substrate includes a base substrate, driver chips, input transmission lines, and output transmission lines, and coupling transmission lines. The driver chips are arranged on a surface of the base substrate. The input transmission lines are formed on the surface of the base substrate, and are electrically coupled to the input terminals of the driver chips. The output transmission lines are formed on the surface of the base substrate, and are electrically coupled to the output terminals of the driver chips. The coupling transmission lines electrically couple the input transmission lines and the output transmission lines.
In this way, on the flexible substrate in Patent Literature 1, coupling transmission lines for electrically coupling the input transmission lines and the output transmission lines are formed to reduce the wiring resistance in the flexible circuit substrate.